Scalable Nanomanufacturing Research Articles

An overview of the translation of selective semiconducting gas sensors from first results to automotive exhaust gas monitors to a platform for breath-based diagnostics

Metal oxide-based resistive gas sensors with inherent selectivity to gases exhaled in a human breath were developed in a scalable and affordable manner. The developments in the tailored synthesis and scalable nanomanufacturing of polymorphs of binary metal oxide gas-sensing elements, together with the publication of guidelines from the medical community for the measurement of breath gases in exhaled breath, have opened the pathway for personalized diagnostic breathalyzers, as described here.

Production of Immunoabsorbent Nanoparticles by Displaying Single-Domain Protein A on Potato Virus X.

The combination of antibodies with nanoparticles provides wide-ranging applications in biosensing. While several covalent presentation strategies have been established, there is need for alternative, non-covalent methods to provide a routine for scalable nanomanufacturing. We report the multivalent presentation of the B domain of Staphylococcus aureus protein A (SpAB) on potato virus X (PVX) nanoparticles. Three different synthetic strategies were used to obtain chimeric PVX(SpAB) filaments. The protein A fragments displayed on the surface of all three PVX chimeras remained fully functional as an immunoabsorbent for antibody capture enabling biosensing. The new biomaterials presented could find applications as diagnostic tools for biomedical or environmental monitoring.

Roll-to-Roll Nanomanufacturing of Hybrid Nanostructures for Energy Storage Device Design.

A key limitation to the practical incorporation of nanostructured materials into emerging applications is the challenge of achieving low-cost, high throughput, and highly replicable scalable nanomanufacturing techniques to produce functional materials. Here, we report a benchtop roll-to-roll technique that builds upon the use of binary solutions of nanomaterials and liquid electrophoretic assembly to rapidly construct hybrid materials for battery design applications. We demonstrate surfactant-free hybrid mixtures of carbon nanotubes, silicon nanoparticles, MoS2 nanosheets, carbon nanohorns, and graphene nanoplatelets. Roll-to-roll electrophoretic assembly from these solutions enables the controlled fabrication of homogeneous coatings of these nanostructures that maintain chemical and physical properties defined by the synergistic combination of nanomaterials utilized without adverse effects of surfactants or impurities that typically limit liquid nanomanufacturing routes. To demonstrate the utility of this nanomanufacturing approach, we employed roll-to-roll electrophoretic processing to fabricate both positive and negative electrodes for lithium ion batteries in less than 30 s. The optimized full-cell battery, containing active materials of prelithiated silicon nanoparticles and MoS2 nanosheets, was assessed to exhibit energy densities of 167 Wh/kgcell(-1) and power densities of 9.6 kW/kgcell(-1).

Scalable nanomanufacturing of surfactant-free carbon nanotube inks for spray coatings with high conductivity

Spray-coated carbon nanotube films offer a simple and printable solution for fabricating low cost, lightweight, and flexible thin-film electronics. However, current nanotube spray inks require either a disruptive surfactant or destructive surface functionalization to stabilize dispersions at the cost of the electrical properties of the deposited film. We demonstrate that high-purity few-walled carbon nanotubes may be stabilized in isopropanol after surface functionalization and that optimizing the ink stability dramatically enhances the conductivity of subsequent spray-coated thin films. We consequently report a surfactant-free carbon nanotube ink for spray-coated thin films with conductivities reaching 2,100 S/cm. Zeta-potential measurements, used to quantify the nanotube ink dispersion quality, directly demonstrate a positive correlation with the spraycoated film conductivity, which is the key metric for high-performance printed electronics.

롤압연, 압출, 단조 등 전통 기계가공법의 모사 응용을 통한 다양한 나노패턴의 대면적 연속생산 기술 구현

We present a series of simple but novel nanopatterning methodologies inspired by traditional mechanical machining processes involving rolling, pullout, and forging. First, we introduce roll-to-roll nanopatterning, which adapts conventional rolling for continuous nanopatterning. Then, nano-inscribing and nano-channel lithography are demonstrated, whereby seamless nanogratings can be continuously pulled out, as in a pullout process. Finally, we discuss vibrational indentation micro- and nanopatterning. Similarly to the forging/indentation process, this technique employs high-frequency vertical vibration to indent periodic micro/nanogratings onto a horizontally fed substrate. We discuss the basic principles of each process, along with its advantages, disadvantages, and potential applications. Adopting mature and reliable traditional technologies for small-scale machining may allow continuous nanopatterning techniques to cope with scalable and low-cost nanomanufacturing in a more productive and trustworthy way.

Mass Transport in Nanowire Synthesis: An Overview of Scalable Nanomanufacturing

The ability to rationally engineer the growth and nanomanufacturing of one-dimensional nanowires in high volumes has the potential to enable applications of nanoscale materials in a diverse range of fields including energy conversion and storage, catalysis, sensing, medicine, and information technology. This review provides a roadmap for the development of large-scale nanowire processing. While myriad techniques exist for bench-scale nanowire synthesis, these growth strategies typically fall within two major categories: 1) anisotropically-catalyzed growth and 2) confined, template-based growth. However, comparisons between growth methods with different mass transport pathways have led to confusion in interpreting observations, in particular Gibbs–Thomson effects. We review mass transport in nanowire synthesis techniques to unify growth models and to allow for direct comparison of observations across different methods. In addition, we discuss the applicability of nanoscale, Gibbs–Thomson effects on mass transport and provide guidelines for the development of new growth models. We explore the scalability of these complex processes with dimensionless numbers and consider the effects of pressure, temperature, and precursor material on nanowire growth.

Tunable synthesis of self-assembled cyclic peptide nanotubes and nanoparticles.

While tremendous efforts have been made in investigating scalable approaches for fabricating nanoparticles, less progress has been made in scalable synthesis of cyclic peptide nanoparticles and nanotubes, despite their great potential for broader biomedical applications. In this paper, tunable synthesis of self-assembled cyclic peptide nanotubes and nanoparticles using three different methods, phase equilibrium, pH-driven, and pH-sensitive methods, were proposed and investigated. The goal is scalable nanomanufacturing of cyclic peptide nanoparticles and nanotubes with different sizes in large quality by controlling multiple process parameters. Cyclo-(L-Gln-D-Ala-L-Glu-D-Ala-)2 was applied to illustrate the proposed ideas. In the study, mass spectrometry and high performance liquid chromatography were employed to verify the chemical structures and purity of the cyclic peptides. Morphology and size of the synthesized nanomaterials were characterized using atomic force microscopy and dynamic light scattering. The dimensions of the self-assembled nanostructures were found to be strongly influenced by the cyclic peptide concentration, side chain modification, pH values, reaction time, stirring intensity, and sonication time. This paper proposed an overall strategy to integrate all the parameters to achieve optimal synthesis outputs. Mechanisms of the self-assembly of the cyclic peptide nanotubes and nanoparticles under variable conditions and tunable parameters were discussed. This study contributes to scalable nanomanufacturing of cyclic peptide based self-assembled nanoparticles and nanotubes for broader biomedical applications.

Recent Progress in Scalable Nanomanufacturing

As the size of materials becomes close to 10 nm, materials exhibit a unique electronic band structure that is not observed in traditional bulk materials. The modified band structure offers new opportunities for future technological innovation because it exhibits unprecedented electrical, optical and magnetic properties that are absent in their bulk counterparts. Fabrication and manufacturing of such novel nanomaterials have been significantly improved in the past few years. The section sponsored by the Nanomaterials Committee in the January issue of JOM has a unique combination of short review papers and research papers on the scale-up and integration of nanomaterials into functional architectures and bulk systems for engineering applications. A paper written by Graeve et al. shows recent progress and current status of spark plasma sintering (SPS) which is beneficial in manufacturing of bulk materials comprised of nanosize grains. Manufacturing of nanostructured bulk material has been a daunting challenge, since the dramatic growth of nanocrystals is accompanied by the densification during the sintering. SPS addresses this trade-off between densification and grain growth. In this paper, principles of SPS sintering and materials prepared by SPS are summarized, showing that various materials (metal, ceramics and polymers) can be sintered without substantial growth of nanosize particles in SPS. In addition, SPS has an economic benefit over other sintering techniques such as hot press, reducing equipment cost and electricity consumption, and increasing a throughput rate. Technical and economical strengths of SPS indicate that SPS may pave a way toward commercialization of bulk nanostructured materials. Therefore, interest in SPS continues to grow in academic and industrial communities. Currently remaining tasks for the commercialization of SPS are near-net and net-shape forming, scalability, and high-throughput systems, and several groups are working to solve these problems. Two-dimensional (2-D) dimensional materials are very attractive, since electrons confined in 2-D planes produce intriguing responses to external optical, electrical, magnetic, and thermal stimuli. Graphene is a well-known 2-D material which exhibits extremely

Growth process modeling of semiconductor nanowires for scale-up of nanomanufacturing: A review

To keep up with the increasing need for nanomanufacturing (NM), research on the scale-up of NM has become an emerging field of study. This review article first discusses the author understanding on research classification of scale-up NM research, which entails scale-up process research and scale-up methodology research. The scale-up methodology research includes establishing modeling, simulation, and control methodologies that enable and support economic production at commercial scale. Since NM process modeling provides the basis for process monitoring and control, guided inspection and sensing strategy, and more-efficient experimental design strategy for robust synthesis of nanomaterials, semiconductor nanowire growth is used as an example to review different process modeling strategies for scalable NM. The modeling strategies from the existing literature on nanowire growth studies are summarized into four categories: (i) physical modeling; (ii) statistical modeling; (iii) physical-statistical modeling; and (iv) cross-domain modeling and validation. In addition to illustrating modeling approaches in the literature, suitable domains of applications for each modeling strategy are discussed. Two potential areas worthy of efforts in future research are highlighted.

Molecular dynamics modeling of water nanodroplet spreading on topographically patterned silicon dioxide and silicon nitride substrates

This article reports the investigation of the spreading behavior of a nanodroplet in a droplet-based scalable nanomanufacturing process using Molecular Dynamics (MD) modeling and simulation. The objective of the study is to understand the effect of substrate topology on the wetting behavior of nanodroplets at the molecular level. A water nanodroplet spreading on silicon dioxide (SiO2) and silicon nitride (Si3N4) substrates with different topologies was studied. A migration of the SiO2–water system from a hydrophilic to hydrophobic interaction was observed with an increase in the aspect ratio of the patterns. In contrast, for the Si3N4–water system the fluid–structural interaction shifted from a hydrophobic to hydrophilic behavior for patterns with corresponding higher aspect ratios. The MD models were validated using molecular kinetic theory. This research provides a foundation for extending the functional range of substrate and solvent combinations by manipulating the substrate topology. The results of this work are expected to serve in the effective control of the hydrophobic/hydrophilic nature of the substrates and therefore aid in the prediction of nanofeature deposition in droplet-based micro/nanomanufacturing processes.

Biotemplates: Scalable Nanomanufacturing of Virus‐templated Coatings for Enhanced Boiling (Adv. Mater. Interfaces 2/2014)

Phase-change heat transfer is used in a variety of large-scale applications and plays a critical role in the production and consumption of energy. As such, there is a need to develop scalable manufacturing strategies for the implementation of robust nanostructured coatings to enhance these processes through interfacial engineering. In article 1300107, M. McCarthy and co-workers demonstrate the use of biological templates for the scalable nanomanufacturing of virusstructured coatings showing enhanced pool boiling performance.

Scalable, Semicontinuous Production of Micelles Encapsulating Nanoparticles via Electrospray

Nanoparticle encapsulation within micelles has been demonstrated as a versatile platform for creating water-soluble nanocomposites. However, in contrast to typical micelle encapsulants, such as small molecule drugs and proteins, nanoparticles are substantially larger, which creates significant challenges in micelle synthesis, especially at large scale. Here, we describe a new nanocomposite synthesis method that combines electrospray, a top-down, continuous manufacturing technology currently used for polymer microparticle fabrication, with bottom-up micellar self-assembly to yield a scalable, semicontinuous micelle synthesis method: i.e., micellar electrospray. Empty micelles and micellar nanocomposites containing quantum dots (QDs), superparamagnetic iron oxide nanoparticles (SPIONs), and their combination were produced using micellar electrospray with a 30-fold increase in yield by weight over batch methods. Particles were characterized using dynamic light scattering, transmission electron microscopy, and scanning mobility particle sizing, with remarkable agreement between methods, which indicated size distributions with variations of as little as ~5%. In addition, new methodologies for qualitatively evaluating nanoparticle loading in the resultant micelles are presented. Micellar electrospray is a broad, scalable nanomanufacturing approach that should be easily adapted to virtually any hydrophobic molecule or nanoparticle with a diameter smaller than the micelle core, potentially enabling synthesis of a vast array of nanocomposites and self-assembled nanostructures.

Scalable Nanomanufacturing of Virus‐templated Coatings for Enhanced Boiling

Scalable Nanomanufacturing of Virus‐templated Coatings for Enhanced Boiling

Molecular dynamics modelling of water nanodroplet impingement on silicon dioxide and silicon nitride substrates

This paper reports the study of a droplet-based scalable micro/nanomanufacturing process using molecular dynamics (MD) modelling. The objective of the study is to understand the nanodroplet impingement and spreading mechanism on silicon dioxide (SiO 2 ) and silicon nitride (Si 3 N 4 ) substrates with different impingement velocities. The dependence of dynamic contact angle on the initial droplet velocity was investigated for hydrophilic and hydrophobic substrate interactions. Higher rebound effect and thereby slower wetting rates were observed for the SiO 2 -water system as compared to the Si 3 N 4 -water system for the same magnitudes of impingement velocities. The MD simulation results were validated using the molecular kinetic theory. Findings of this research are expected to establish the required process controls in droplet-based scalable nanomanufacturing for precision deposition of nanoscale features.

CHARACTERIZATION AND TOXICITY OF CARBON DOT-POLY(LACTIC-CO-GLYCOLIC ACID) NANOCOMPOSITES FOR BIOMEDICAL IMAGING

Semiconductor quantum dots (QDs) have achieved initial success as biomedical imaging agents. However, significant cytotoxicity in the biological environment prohibits their use in vivo. Here, we introduce nanocomposites composed of carbon dots (C-dots) in poly(lactic-co-glycolic acid) (PLGA) carriers as possible imaging agents for in vivo applications. An initial hurdle to clinical use is overcome by synthesizing C-dots with commercially available carbon black precursors, permitting scalable nanomanufacturing. These fluorescent nanoparticles, which have a mean diameter of ~1 nm, display a disordered graphitic structure. To overcome a second clinical hurdle (i.e., rapid renal clearance of nanoparticles <~6 nm in diameter), C-dots were encapsulated in biodegradable PLGA nanospheres. The resulting nanocomposites showed a mean diameter of 344 ± 23 nm, which should reduce renal clearance. With further optimization, nanocarriers could be optimized to sizes <200 nm to reduce accumulation in the reticuloendothelial system (RES). Toxicity of both C-dots and C-dot-PLGA nanocomposites was evaluated using HepG2 liver cell lines. Unlike QDs, which can induce toxicological responses at concentrations as low as 0.005 mg/mL, C-dots exhibited cytotoxicity at concentrations greater than 0.2 mg/mL, while their derived nanocomposites did not exhibit cytotoxicity at any concentration tested (i.e., 0.02 mg/mL, 0.1 mg/mL and 0.2 mg/mL).

Scalable High-Power Redox Capacitors with Aligned Nanoforests of Crystalline MnO2Nanorods by High Voltage Electrophoretic Deposition

It is commonly perceived that reduction-oxidation (redox) capacitors have to sacrifice power density to achieve higher energy density than carbon-based electric double layer capacitors. In this work, we report the synergetic advantages of combining the high crystallinity of hydrothermally synthesized α-MnO2 nanorods with alignment for high performance redox capacitors. Such an approach is enabled by high voltage electrophoretic deposition (HVEPD) technology which can obtain vertically aligned nanoforests with great process versatility. The scalable nanomanufacturing process is demonstrated by roll-printing an aligned forest of α-MnO2 nanorods on a large flexible substrate (1 inch by 1 foot). The electrodes show very high power density (340 kW/kg at an energy density of 4.7 Wh/kg) and excellent cyclability (over 92% capacitance retention over 2000 cycles). Pretreatment of the substrate and use of a conductive holding layer have also been shown to significantly reduce the contact resistance between the aligned nanoforests and the substrates. High areal specific capacitances of around 8500 μF/cm(2) have been obtained for each electrode with a two-electrode device configuration. Over 93% capacitance retention was observed when the cycling current densities were increased from 0.25 to 10 mA/cm(2), indicating high rate capabilities of the fabricated electrodes and resulting in the very high attainable power density. The high performance of the electrodes is attributed to the crystallographic structure, 1D morphology, aligned orientation, and low contact resistance.

Transport Characteristics of Multichannel Transistors Made from Densely Aligned Sub-10 nm Half-Pitch Graphene Nanoribbons

Densely aligned sub-10 nm graphene nanoribbons are desirable for scale-up applications in nanoelectronics. We implemented directed self-assembly of block-copolymers in combination with nanoimprint lithography to pattern sub-10 nm half-pitch nanoribbons over large areas. These graphene nanoribbons have the highest density and uniformity to date. Multichannel field-effect transistors were made from such nanoribbons, and the transport characteristics of transistors were studied. Our work indicates that a large ribbon-to-ribbon width variation in a multichannel FET can lead to nonsynchronized switching characters of multiple graphene channels and thus a poor ON/OFF current ratio. Through process optimization, we have created 8 nm half-pitch graphene nanoribbons with the minimal ribbon-to-ribbon width variation of ∼2.4 nm (3σ value). The corresponding transistors exhibit an ON/OFF current ratio >10, which is among the highest values ever reported for transistors consisting of densely arranged graphene nanoribbons. This work provides important insights for optimizing the uniformity and transport properties of lithographically patterned graphene nanostructures. In addition, the presented fabrication route could be further developed for the scalable nanomanufacturing of graphene-based nanoelectronic devices over large areas.

High Voltage Electrophoretic Deposition of Aligned Nanoforests for Scalable Nanomanufacturing of Electrochemical Energy Storage Devices

High voltage electrophoretic deposition (HVEPD) has been used to obtain forests of aligned multi-walled carbon nanotubes (MWCNTs) on long strips of flexible, conductive substrates. Successful design and integration of a continuous HVEPD setup has enabled scalable fabrication of electrodes for electrochemical energy storage. The mechanism of continuous HVEPD has been investigated to ensure appropriate alignment. Well-aligned forests of MWCNTs were obtained using a conductive holding layer which helped reduce internal resistance and enhance the electrochemical performance of the electrodes.

Scalable nanomanufacturing of millimetre-length 2D NaxCoO2 nanosheets

A novel, scalable nanomanufacturing technique is reported for batch fabrication of nanoscale-thick Na0.7CoO2 nanosheets. The nanomanufacturing technique is a high-yield, bottom-up process that is capable of producing tens of thousands of nanosheets stacked into a macro-scale pellet. The nanosheets are uniform in length and shape with very high crystal anisotropy. The nanosheet thicknesses can be 10–100 nm while their lengths can measure up to 1.8 mm long. The typical dimension ratios are highly anisotropic, at 10−5:1 : 1 (thickness:length:width). X-ray synchrotron studies indicate that the 2D crystals are stacked in a turbostratic arrangement with rotational misalignment with respect to the stacking axis. The stacked nanosheets are readily delaminated into very large (350 μm × 150 μm × 100 nm) free-standing 2D crystals. The novel nanomanufacturing technique is based on sol–gel and electric-field induced kinetic-demixing followed by a brief high temperature treatment, thus providing an efficient means of large scale crystal growth requiring only a simple furnace and power supply. Evidence shows that the demixing process increases the concentration of Na ions and that demixing is necessary to produce the millimetre-length nanosheets. Electric field induced kinetic-demixing is successfully performed at low temperatures (<300 °C), which is more than three times lower than past kinetic-demixing temperatures.

Formation of silicon nanodots via ion beam sputtering of ultrathin gold thin film coatings on Si

Ion beam sputtering of ultrathin film Au coatings used as a physical catalyst for self-organization of Si nanostructures has been achieved by tuning the incident particle energy. This approach holds promise as a scalable nanomanufacturing parallel processing alternative to candidate nanolithography techniques. Structures of 11- to 14-nm Si nanodots are formed with normal incidence low-energy Ar ions of 200 eV and fluences above 2 × 1017 cm-2. In situ surface characterization during ion irradiation elucidates early stage ion mixing migration mechanism for nanodot self-organization. In particular, the evolution from gold film islands to the formation of ion-induced metastable gold silicide followed by pure Si nanodots formed with no need for impurity seeding.